JPH1081960A - Sputtering target for forming optical recording protective coating with limited generation of particle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target for forming optical recording protective coating composed of a zinc sulfide-silicon dioxide sintered body, generating a limited amount particles and used for optical media executing the recording and erasing of information by using light beams. SOLUTION: This sputtering target is composed of a sintered body having a compsn. contg. 10 to 30mol% silicon dioxide having >=99.999wt.% purity, furthermore contg., at need, 10 to 1000ppm aluminum oxide, and the balance zinc sulfide having >=99.999wt.% purity and furthermore having >=90% relative density. In this case, as for the zinc sulfide, the coexisting ratio of (α/β) of αtype crystals to β type crystals lies in the range of 0.95<α/β<100, moreover, the maximum grain diameter of the α type crystals and the β type crystals is regulated to <=15μm, and also, the average grain diameter is regulated to <=10μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target comprising a zinc sulfide-silicon dioxide sintered body for forming a protective film used for an optical medium such as an optical disk for recording and erasing information using a light beam. More particularly, the present invention relates to a sputtering target in which particles are less generated during sputtering.

[0002]

2. Description of the Related Art As a sputtering target for forming a protective film used for an optical medium such as an optical disk for recording and erasing information using a light beam, silicon dioxide having a purity of 99.999% by weight or more and a purity of: 9
2. Description of the Related Art A sputtering target composed of a sintered body having a zinc sulfide content of 9.999% by weight or more and a relative density of 90% or more is known (see JP-A-6-65725). This conventional sputtering target for forming an optical recording protective film is prepared by adding 20 mol% of silicon dioxide powder having a purity of 99.999% by weight or more to zinc sulfide powder having a purity of 99.999% by weight or more and mixing uniformly. It is also known to produce the mixed powder by sintering it after pressing.

Further, zinc sulfide generally has two crystal forms, α-type crystal and β-type crystal. The α-type crystal has a hexagonal wurtzite-type structure and is stable at high temperatures, while the β-type crystal Is known to have a zinc blende structure and to be stable at room temperature, and to have a transition temperature of 1020 ° C. between α-type crystal and β-type crystal.

[0004]

In recent years, the requirements for the performance of an optical recording protective film have become increasingly severe, and in particular, the requirements for suppressing particles generated during sputtering have become severe. Although a target that generates less particles during sputtering is required, a target that generates less particles during sputtering has not yet been obtained.

[0005]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of conducting research to obtain a target with less generation of particles during sputtering, (a) purity: 99.
999% by weight or more of silicon dioxide: 10 to 30 mol%
In a sputtering target comprising a sintered body having a composition consisting of zinc sulfide having a purity of 99.999% by weight or more, the crystal form of the zinc sulfide greatly affects particle generation during sputtering,
When the mixture ratio of α-type crystals and β-type crystals (α / β) is in the range of 0.95 <α / β <100, zinc sulfide suppresses particle generation during sputtering, and the value of α / β becomes (B) The crystal size of the zinc sulfide α-type crystal and β-type crystal contained in the sputtering target is large in the generation of particles during sputtering. Affect, α
The maximum and average crystal grain sizes of the type crystal and the β type crystal are preferably as small as possible.
(c) Purity: 99.999% by weight or more of zinc sulfide powder, purity: 99.999% by weight or more of silicon dioxide powder: 10 to 10 μm or less. 30 mol% is added, and 10 to 1000 ppm of aluminum oxide powder is further added,
The sputtering target obtained by hot-pressing the mixed powder obtained by mixing them has improved knowledge on mechanical properties to improve sinterability, and does not crack during sputtering. It was.

The present invention has been made on the basis of the above findings. (1) Purity: 99.999% by weight or more of silicon dioxide: 10 to 30 mol%, the balance being purity: 99.999% In a sputtering target composed of a sintered body having a composition comprising at least 90% by weight and a composition comprising at least 90% by weight of zinc sulfide, the zinc sulfide has a mixture ratio of α-type crystal and β-type crystal (α / β) of 0.1%. 95 <
α / β <100 (preferably 1.0 ≦ α / β ≦ 50)
(2) Purity: 99. A sputtering target for forming an optical recording protective film with less generation of particles in the range of (2).
999% by weight or more of silicon dioxide: 10 to 30 mol
%, Aluminum oxide: 10 to 1000 ppm, the balance being a composition comprising zinc sulfide having a purity of 99.999% by weight or more, and a relative density: a sputtering target comprising a sintered body having a content of 90% or more, Zinc sulfide has a mixture ratio of α-type crystals and β-type crystals (α / β) of 0.95 <α / β <100 (preferably 1.0 ≦ α /
β ≦ 50), a sputtering target for forming an optical recording protection film with less generation of particles, (3) α-type zinc sulfide contained in the sputtering targets for forming an optical recording protection film of the above (1) and (2). Crystal and β
The present invention is characterized in that the sputtering target for forming an optical recording protective film with less generation of particles has a maximum crystal grain size of 15 μm or less and an average crystal grain size of 10 μm or less.

The sputtering target for forming an optical recording protective film according to the present invention is obtained by adding 10 to 30 mol% of silicon dioxide powder having a purity of 99.999 wt% or more to zinc sulfide having a heat treatment purity of 99.999 wt% or more. Then, the powder is manufactured by hot-pressing a mixed powder obtained by uniformly mixing these. To further improve sinterability and mechanical strength, aluminum oxide powder
Add 0-1000 ppm.

The amount of aluminum oxide contained in the sputtering target for forming an optical recording protective film of the present invention is 10 to
The reason for limiting to 1000 ppm is that if the addition amount of aluminum oxide is less than 10 ppm, the sinterability is not sufficiently improved, so that sufficient mechanical strength cannot be obtained.
When the content exceeds m, the quality of the obtained optical recording protective film is deteriorated, which is not preferable. The more preferable range of the amount of aluminum oxide contained in the sputtering target for forming an optical recording protective film of the present invention is 15
0 to 400 ppm.

In order to control the mixture ratio (α / β) of α-type crystals and β-type crystals of zinc sulfide so as to be in the range of 0.95 <α / β <100, zinc sulfide powder is 910-1100.
6 ° C at a temperature of 10 ° C (preferably 1050 to 1100 ° C).
After holding for 10 hours, a heat treatment for cooling is performed at a cooling rate from the holding temperature to 200 ° C. at a rate of 2 to 5 ° C./min, and the sintering conditions are Ar gas atmosphere, pressure: 150 to 200 kg.
f / cm ² , temperature: 1100 to 1150 ° C. (preferably 1120 to 1150 ° C.), and after holding for 6 to 12 hours, the temperature from this holding temperature to 200 ° C. is 2 to 5 ° C./min.
It is obtained by cooling to a temperature of 100 ° C. or lower at a cooling rate within the range described above, and taking out. The thus-obtained sputtering target for forming an optical recording protective film of the present invention can be applied to any sputtering apparatus, and particularly when used as a target of a single-wafer sputtering apparatus,
The number of particles generated during sputtering is particularly small, which is effective.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION As raw material powder, particle size: 4 ± 1μ
m and a purity: 99.999% by weight or more of ZnS powder;
An SiO ₂ powder having an average particle diameter of 10 μm and a purity of 99.999% by weight or more and an Al ₂ O ₃ powder having an average particle diameter of 1 μm and a purity of 99.99% by weight or more are prepared.
The ZnS powder was subjected to a heat treatment under the conditions shown in Table 1 in an Ar gas atmosphere to produce ZnS powders A to H. However, ZnS powder H is a powder that is not heat-treated.

[0011]

[Table 1]

Example 1 The heat-treated ZnS powders A to G and the non-heat-treated ZnS powders Z
Table 2 shows the prepared SiO ₂ powder with respect to nS powder H.
And mixed by stirring in a ball mill for 20 hours. The obtained mixed powder was filled in a graphite mold of a hot press, and in an argon atmosphere, under the conditions of pressure, temperature and time retention shown in Table 2, By hot pressing, it has the component composition, relative density, α / β and maximum crystal grain diameter and average crystal grain diameter of α-type crystal and β-type crystal of zinc sulfide shown in Table 3, and further has a diameter of 125 mm, Thickness: Disc-shaped targets 1 to 12 of the present invention having a dimension of 5 mm, comparative target 1 and a conventional target were manufactured.

The α / β of the zinc sulfides of the targets 1 to 12 of the present invention, the comparative target 1 and the conventional target were respectively the first peak values (100) obtained by X-ray diffraction.
α and (111) β were measured to determine the ratio. On the other hand, the crystal grain sizes of the targets 1 to 12 of the present invention, the comparative target 1 and the conventional target were obtained by polishing the cross section of the sintered body using a diamond paste. And a scanning electron microscope.

The targets 1 to 12 of the present invention, the comparative target 1 and the conventional target were soldered to a copper backing plate for cooling, and this was set in a single-wafer type high-frequency magnetron sputtering apparatus as shown in FIG. , Sputtering gas: Ar, sputtering gas pressure:
Sputtering was performed under the conditions of 5 × 10 ⁻³ Torr, a sputtering time of 1 minute and 5 minutes, and a power of 600 W, and the number of particles after 1 minute and after 5 minutes of sputtering was measured by a particle counter. Are shown in Table 3.

In FIG. 1, 1 is a target, 2
Denotes a backing plate, 3 denotes a substrate electrode, 4 denotes a substrate, 5 denotes a gate valve, 6 denotes a sputtering chamber, 7 denotes a transfer chamber, 8 denotes a storage chamber, and 9 denotes sputtered particles. In the single-wafer sputtering apparatus, the pre-transfer substrate 4-1 is stored in the transfer chamber 7, and the pre-transfer substrate 4-1 is stored.
Through the gate valve 5 to the substrate electrode 3 one by one,
After depositing the sputtered particles 9 to form a sputtered film,
It is stored in the storage chamber 8.

[0016]

[Table 2]

[0017]

[Table 3]

From the results shown in Tables 2 and 3, 600 W
It can be seen that when sputtering is performed with a high output power and a high film forming rate, the targets 1 to 12 of the present invention generate a smaller amount of particles than the comparative target 1 and the conventional target.

[0019] with respect to ZnS powder H not ZnS powder A~G and heat treatment were heat-treated as shown in Example 2 in Table 1, SiO ₂ powder and A
l ₂ O ₃ powder was blended at the ratio shown in Table 4 and hot-pressed in an argon atmosphere under the conditions of pressure, temperature and time shown in Table 4 to obtain the component composition and relative density shown in Table 5. , Α / β and zinc sulfide Disc-shaped targets 13 to 22 of the present invention having the maximum crystal grain diameter and average crystal grain diameter of α-type crystal and β-type crystal, and having a diameter of 125 mm and a thickness of 5 mm. Was manufactured.

The targets 13 to 22 of the present invention were soldered to a cooling backing plate made of copper, which was set in a single-wafer type high-frequency magnetron sputtering apparatus in exactly the same manner as in Example 1; Gas pressure: 5 × 10 ⁻³ Torr, sputtering time:
Sputtering was performed for 1 minute and 5 minutes under the condition of electric power: 600 W. After the 1 minute sputtering was completed and after the 5 minute sputtering was completed, the number of particles was measured with a particle counter. Table 5 shows the results.

[0021]

[Table 4]

[0022]

[Table 5]

From the results shown in Tables 4 and 5, Al ₂ O
₃ to 10 to 1000 ppm of the present target 13 to
22 shows the case where sputtering was performed by applying a high output of 600 W and increasing the film forming rate, and Table 2 prepared in Example 1 was used.
It can also be seen that the amount of generated particles is smaller than that of the comparative target 1 and the conventional target shown in Table 3, and no cracks are generated even when the sputtering is completed, so that the deposition rate can be increased.

[0024]

As described above, the sputtering target for forming an optical recording protection film according to the present invention has a small number of particles even when high-power sputtering is performed, and is free from cracks. Since a sputtering target can be provided, it can greatly contribute to the development of the optical media industry.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view of a single-wafer sputtering apparatus suitable for using a sputtering target for forming an optical recording protective film of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Target 2 Backing plate 3 Substrate electrode 4 Substrate 5 Gate valve 6 Sputter chamber 7 Transfer chamber 8 Storage chamber 9 Sputtered particles

Claims (3)

[Claims] 1. Purity: 99.999% by weight or more of silicon dioxide: 10 to 30 mol%, the balance being 9:
In a sputtering target composed of a sintered body having a composition of 9.999% by weight or more of zinc sulfide and a relative density of 90% or more, the zinc sulfide is a mixture ratio of α-type crystals and β-type crystals (α /
β) is in the range of 0.95 <α / β <100. A sputtering target for forming an optical recording protective film with less generation of particles. 2. Purity: 99.999% by weight or more of silicon dioxide: 10 to 30 mol%, aluminum oxide: 10
１０００1000 ppm, the balance being purity: 99.999
Composition comprising more than 1% by weight of zinc sulfide, and relative density:
A sputtering target comprising a sintered body having 90% or more, wherein the zinc sulfide is a mixture ratio of α-type crystals and β-type crystals (α /
β) is in the range of 0.95 <α / β <100. A sputtering target for forming an optical recording protective film with less generation of particles. 3. The maximum crystal grain size of the α-type crystal and β-type crystal of the zinc sulfide is 15 μm or less and the average crystal particle size is 1 μm.
3. The sputtering target for forming an optical recording protective film according to claim 1, wherein the thickness is 0 [mu] m or less.